Today we're going to talk about what an ear even is, how ears have evolved, how they work, and some of the cool ways animals have tweaked their ears to work for their lifestyle. So perk up whatever you use for hearing because we're going to be sending vibrations your way for the next 10ish minutes!

One of the most common adaptations seen in the animal kingdom is vision. Nearly 96% of all animals have some kind of eyes and they've proven so evolutionary advantageous that they've evolved multiple times in multiple ways and in a surprisingly short amount of time! So today, we'll walk you through the different types of eyes, show you how they work, and even take you on the day in the life of one of the most complex visual systems ever discovered in the mantis shrimp!

Yep, this is the poop episode. Getting resources and getting rid of waste is so important, we have three whole systems dedicated to it! In this episode, we’ll learn how the respiratory system, digestive system, and urinary system work, and visit some other animals that process their resources in completely different (and sometimes totally wild) ways.
Chapters:
Introduction: C. diff
The Respiratory System
Ingestion & Digestion
Absorption & Propulsion
Defecation
The Urinary System
Review & Credits
Credits

Today we’re going to take a closer look at cities, examine how these large complex structures are organized, and identify patterns and differences in land use around the world. We'll begin with a quick recap of Central Place Theory, then we'll show you how the Concentric Zone Model can approximate the development of Chicago in the United States. Then, we'll take a closer look at colonial port cities, the development of industrial zones and financial districts, and the patchwork of immigrant communities that often developed around them in cities such as Boston in the United States. And finally, we will end our episode with a look at the layout of some North African cities that are in earthquake-prone areas with hot and dry climates such as in Fez, Morocco.

Over the course of this series, we've seen that outbreak science is actually MANY sciences, including biology, epidemiology, sociology, and even economics! Because outbreak science is an interdisciplinary field, everyone has a role to play in ending outbreaks, including you! In this final episode of Crash Course Outbreak Science, we'll take a look at how different fields come together to prepare for and prevent outbreaks.

In 1959, the WHO set out to eradicate smallpox, an ambitious goal that was achieved by 1980. But this goal wouldn't have been possible without coordination on all levels of society. In this episode of Crash Course Outbreak Science, we'll look at cooperation on the individual, community, and national scale and see how by working together we can improve outcomes during an outbreak, prevent future outbreaks, and even eradicate disease.

When you think about the technology that helps us prevent outbreaks, what do you think of? Vaccines? Lab tests? Medications? What about toilets? That's right! Toilets are an important piece of technology that can help us prevent outbreaks! Toilets are a part of infrastructure, the important system that we'll be talking about in this episode of Crash Course Outbreak Science. We'll look at how from physical infrastructure, from toilets, to sewers, to roads, and more, creates healthier environments for us and helps us prevent and deal with outbreaks.

If you compare precipitation around the world with population distribution we can understand a simple but powerful pattern of human geography: where there is water, there are people. But it gets a little more complicated because where there are people and limited resources, there is often conflict and bigger geographical questions at stake. So today, we’re going to zoom in and look more closely at how precipitation patterns around the Great Plains and the western United States has led to many conflicts involving the use and distribution of water resources.

Now that we know how complex and interwoven climate change is with society globally, we can begin to see it everywhere. But that heightened awareness also means we can begin to see solutions everywhere. In this episode of Crash Course Climate & Energy, we break down what needs to happen in our governments, corporations, and communities to slow the increase of Earth's average temperature.

Chapters:
Introduction: Slowing Down Climate Change
Limiting Global Warming
A Carbon-Neutral Future
Governments & Corporations
Young People Leading the Climate Movement
Climate Change is Everywhere
People Power Works
Review & Credits
Credits

Decarbonizing our power production is vitally important if we want to curtail climate change, but there are some major logistical issues we’re going to have to overcome before we can do that. In this episode of Crash Course Climate and Energy, we’ll take a look at the challenges we face when creating, distributing, and storing electricity from renewable sources.

Chapters:
Introduction: Storing Carbon-Free Electricity
Electricity As An Energy Carrier
The Electric Grid
Electricity Supply & The Duck Curve
Electrochemical Storage of Electricity
Chemical Storage of Electricity
Mechanical Storage of Electricity
Thermal Storage of Electricity
Transmitting Carbon-Free Electricity
Review & Credits
Credits

Art is often understood as a solitary act of personal expression. But art is also the basis for community from Alaska to Mali — and from gay rights advocates to Frida Kahlo appreciators. In this episode we’ll learn how community is created through art.

Note: While Yayoi Kusama is an incredibly influential artist, she has a complicated legacy. Writer and PhD candidate Dexter Thomas has called attention to anti-Black racism in her published writing, including her 2002 autobiography “Infinity Net.” We encourage you to view Crash Course Art History Episode 5 to hear our discussion about artists with problematic histories and join the conversation.
Chapters:
Introduction: Obliteration Room
The Great Mosque of Djenné
The Gelede
The Chief Johnson Pole
The Origins of Pride Flags
The Umbrella Art of Hong Kong
Review & Credits
Credits

Today we're going to talk about a fundamental part of all modern computers. The thing that basically everything else uses - the Arithmetic and Logic Unit (or the ALU). The ALU may not have to most exciting name, but it is the mathematical brain of a computer and is responsible for all the calculations your computer does! And it's actually not that complicated. So today we're going to use the binary and logic gates we learned in previous episodes to build one from scratch, and then we'll use our newly minted ALU when we construct the heart of a computer, the CPU, in episode 7.

*CORRECTION*

“You shouldn’t make decisions when you’re hungry.” Tell that to the cell that ate a bacterium 1.5 billion years ago and set in motion the evolution of all plants on Earth. In this episode of Crash Course Botany, we’ll explore how plants came to exist, the forces that drive plant evolution, and how we know what Earth’s prehistoric dystopia was like before plants came along.

Chapters:
A World Without Plants
Plants' Origin Story
Defining Evolution
The Five Forces of Evolution
Studying Plant Evolution
Plants' Evolutionary History
Review & Credits
Credits

Today we’re going to talk about the collection of routes known as the Silk Roads, and explore how worldview and other ideas spread along those trade routes. The Silk Roads are responsible for everything from the spices we use when we cook to the cloth we see as beautiful, but today we’re going to focus on religion, and show how these routes influenced the beliefs of billions of people through time and space.

Today, we're going to take a closer look at how the oceans circulate by following the life of a discarded water bottle as it gets snagged in the North Pacific Garbage Patch. We'll talk about what causes the movement of water, called current, both near the surface and much deeper in the oceans, and we'll show how they follow similar (but not identical) paths to the winds. Ocean circulation plays a huge role in cycling vital nutrients within the seas and helps us transport goods on ships across the globe and it's up to us to protect it.

You may not realize it, but your body is like a fortress, designed to defend you from tiny foreign invaders known as pathogens. This seemingly small world is actually super diverse, and sometimes super dangerous too. That’s why in this episode of Crash Course Outbreak Science, we’re going to get familiar with all different types of pathogens like viruses, bacteria, fungi, and more!

From the Egyptian Book of the Dead to Tibetan Buddhist sand mandalas, humans have always reached for art to express religious ideas and impulses. In this episode, we’ll explore how concepts of the divine and spirituality intersect with the history of art.
Chapters:
Introduction: James Hampton
The Book of the Dead
Art & Spiritual Feelings
Sacred Spaces
Art as Prayer & Ritual
Review & Credits
Credits

Humans make stuff up—including the names and classifications of living things. But those categories are still useful. In this episode of Crash Course Botany, we’ll explore how taxonomy and systematics help us understand what plants are and where they come from. We’ll discuss the power of naming, and why even scientists don’t agree on what a species is.

Chapters:
Categorizing Plants
What Is a Plant?
Taxonomy & Systematics
Indigenous Taxonomic Knowledge
Species Concepts
Review & Credits
Credits

At the heart of outbreaks are people! People are the ones who get sick, transmit diseases, and change the way they live in response to outbreaks. In outbreak science, we can better understand the relationship between people and disease through the discipline of epidemiology. In this episode of Crash Course Outbreak Science, we’ll look at what epidemiology is and how it helps us track the spread of diseases, and even stop outbreaks.

Sometimes, diagnosing patients is pretty easy, but other times... not so much. Luckily, in a medical setting we have tools that can help us figure out what's wrong with patients, and how to help them. In this episode of Crash Course Outbreak Science, we'll use clinical symptomatology and diagnostic testing to collect data and test our hypotheses about what may be wrong with some hypothetical patients, and use what we learn to help our patients get better and stop the disease from spreading to more people.